Use of a phosphate mixture for the production of concentrated solutions and brine for the food industry

ABSTRACT

The invention relates to a novel phosphate mixture, which is characterised by the excellent solubility thereof in water and in aqueous solutions containing salt (brine). The novel phosphate mixture is characterised in that it is made of the following components: 1) 60-85 wt. % of a clear-soluble potassium tripolyphosphate having a P 2 O 5  content of 46.0 wt. %-47.0 wt. %, preferably 46.4 46.8 wt. %, especially 46.4 wt % and a K 2 O/P 2 O 5  Mol ratio of 1.70 1.78, preferably 1.73 1.75 and especially 1.74, 2) 15-39 wt. % of sodium polyphosphate NPP, 3.) 1-5 wt. % XH 2 PO 4 , whereby X═Na and is K, whereby the mixture has a pH-value of between 8-10, preferably 8.5 9.5 and has an opacity in water and brine of &lt;5 TE/F.

The subject matter of the present invention is a novel phosphate mixture, characterized by its excellent solubility in water and aqueous solutions containing salt (brines).

Phosphate salts have been used for a long time in the food industry. A great many special uses for phosphates in the food industry, for example their use for the processing of meat, fish, beverages and milk products, are described in the article “Phosphates in food” by Ricardo Molins, CRC Press, 1991. Phosphates represent so-called functional food additives, meaning their use depends on the area of application and is specifically directed toward diverse problem definitions. Responsible for such a wide use spectrum of the phosphates are their properties, which include:

A buffering effect (for the pH adjustment as well as the pH stabilization);

The capacity to form complexes on multi-valent cations and thus indirectly connected the function as anti-oxidant (through bonding of pro-oxidative cations) and as anti-microbial substance, as well as for influencing the consistency;

The function as polyanion in an interaction with different protein fractions of individual food items;

The capacity for souring (for pH adjustment in beverages and as souring component in leavening agents).

The respective function depends on the structure and/or the condensation degree, the pH value and the cation of the salt.

The chemical terms used for the individual phosphates in this invention are as follows:

-   STPP or NTPP sodiumtripolyphosphate -   KTTP potassiumtripolyphosphate -   TKPP tetrapotassiumdiphosphate -   TNPP tetrasodiumdiphosphate -   NPP sodiumpolyphosphate -   KPP potassiumpolyphosphate -   MNP monosodiumphosphate -   DNP disodiumphosphate -   TNP trisodiummonophosphate -   MKP monopotassiumphosphate -   DKP dipotassiumphosphate

According to the present invention, KTPP, TKPP, NPP, MNP and/or MKP are used as phosphate salts.

In addition to the direct admixture of phosphates in the form of a dry substance (powdered form) in the food industry, liquid forms are used for a number of application cases, so-called phosphate solutions or phosphate brines, for example in the area of meat processing (e.g. the production of pickled items for cooking), as well as for treating seafood products (fish filet, crustaceans, types of mollusks, etc.). Phosphates must have the following critical properties to be able to use them effectively and with high functionality:

-   1.) They must have a pH value (aqueous solution) of 8 to 10. -   2.) They must be highly water soluble. -   3.) They must have high solubility in salt-containing solutions     (brines). -   4.) The prepared solutions must be clear and free of residues,     meaning there should be no precipitations and no excess solutes. -   5.) As functional component of the food item with additive, it     should contain a certain share of sodium and/or potassium     diphosphates and/or triphosphates.     A person skilled in the art of the food industry understands brines     to be solutions in which high concentrations of cooking salt (NaCl)     are dissolved up to the point of saturation. A series of     commercially available phosphates and phosphate mixtures for the     meat and fish industry meet individual properties that are required,     but not all of them.     Thus, it is the object of the present invention to find a phosphate     mixture that meets all of the above-stated requirements.

The novel phosphate mixture is characterized in that it comprises the following components:

-   1.) 60 to 85 weight % of a clear soluble potassiumtripolyphosphate     with a P₂O₅ content of 46.0 weight % to 47.0 weight %, preferably     46.4-46.8 weight % and in particular 46.4 weight %, as well as a     K₂O/P₂O₅ mole ratio of 1.74 to 1.78, preferably 1.73 to 1.75, and in     particular 1.74. -   2.) 15 to 39 weight % sodiumpolyphosphate NPP -   3.) 1 to 5 weight % XaH₂PO₄ and/or X₂H₄P₂O₇, with X═Na and K,     wherein the mixture has a pH value of 8 to 10, preferably 8.5 to     9.5, and shows clouding in water and brines of <5TE/F.     The clouding is measured with standard measuring devices for this     technical area.

Essential to the invention is the use of a so-called clear soluble potassium polyphosphate which is extracted from a melt having a P₂O₅ content of 46.0 to 47.0%, preferably 46.4 to 46.8 and especially preferred 46.4% and stoichiometrically consists of a mixture of potassium phosphate and tetrapotassiumdiphosphate at a ratio of approximately 3:1. The melt is produced by mixing corresponding amounts of potassiumphosphates, in particular tripotassiumphosphate with P₂O₅ and heating it to the melting temperature and leaving it at this temperature until the reaction balance is adjusted. A mixture is thus formed which contains only small amounts of orthophosphates and diphosphates in addition to potassiumphosphate and tetrapotassiumdiphosphate, as well as the harder to dissolve potassiummetaphosphates which are responsible for the cloudiness of the polyphosphate solution outside of this narrow range; see phase diagram by J. R. van Wazer, Phosphorous and its compounds, Vol. VI, page 608.

In Tables 1 and 2, the recipe for producing the mixture according to the invention are listed, taking into account that the desired pH value of the mixture according to the invention can be adjusted with the aid of Na/K orthophosphates (Table 1), as well as with Na/K diphosphates (Table 2). TABLE 1 Example for producing the mixture according to the invention by using N/K orthophosphates for the pH value adjustment. min. max. typical orthophosphate 1% 5%  1-2% (M_(x)H_(3−x)PO₄) X = 0-3 M = Na, K clear soluble KTPP 60% 85% 70% (potassiumtripolyphosphate) sodiumpolyphosphate 15% 39% 28-30% with P₂O₅ content of 60-71.5% P₂O₅ content 47 55 50 pH value 8 10  9 clouding (6% solution) <5 TE/F

TABLE 2 Example for producing the mixture according to the invention by using Na/K diphosphates for the pH value adjustment. min. max. typical disodiumphosphate 1% 5%  1-2% (M_(x)H_(4−x)P₂O₇) M = Na and x = [4, 3, 2] and/or M = K and x = 4 clear soluble KTPP 60% 85% 70% (potassiumtripolyphosphate) sodiumpolyphosphate 15% 39% 28-30% with P₂O₅ content of 60-71.5% P₂O₅ content 47 55 50 pH value 8 10  9 clouding (6% solution) <5 TE/F

The main components (sodiumpolyphosphate and potassiumtripolyphosphate) of the mixture according to the invention by themselves show a high solubility limit in water (>50%) (see Table 3). TABLE 3 Solubility limit (in g phosphate mixture per 100 g solution) of the mixture according to the invention as compared to phosphate mixtures based on the prior art: g phosphate/100 g solution Type of phosphate [% m/m] mixture according to the invention 50 pentapotassiumtriphosphate (KTPP) 64 very cloudy! clear soluble KTPP >50 pentasodiumtriphosphate (NTPP) 14 tetrapotassiumdiphosphate (TKPP) 65 NTPP/TNPP - 90:10 blend 17 NTPP/polyphosphate 80:20 blend 16 sodiumpolyphosphate >50

Furthermore, individual main components of the mixture according to the invention have good solubility properties even in brines (see Table 4; Example 1).

The phosphate types and/or phosphate combinations known so far exhibit individual properties of the aforementioned required properties, but not all of them:

Thus, the KTPP mentioned in Table 3 is highly soluble (64 g/100 g solution) and is also soluble in the presence of cooking salt, but is cloudy.

The sodiumpolyphosphates mentioned in Tables 3 and 4 are also highly soluble, but lack the functional shares of diphosphates and triphosphates listed under requirement 5.

By producing a mixture comprising both main components of the mixture according to the invention and an additional phosphate for the pH adjustment (orthophosphate or di-phosphate), synergic effects are used that increase the solubility in highly concentrated brines.

The synergic effect of the mixture according to the invention and its impact on the solubility in salt-containing solutions are demonstrated with the aid of 3 examples shown in Table 4.

Example 1 and Example 2 show a traditional sequence for the solubility, meaning the phosphate type and/or the phosphate combination is dissolved as the first component in water. Following this, the respective amount of sodium chloride (cooking salt) is dissolved.

In the food industry, e.g. for producing cooked ham, it is standard procedure to first dissolve the phosphate in water and then add the cooking salt. The so-called inverse preparation technique is understood to mean that the cooking salt solution (brine) is first produced and the phosphate is then added.

Example 3 additionally shows the synergic effect of the mixture according to the invention. With this mixture, an “inverse sequence” can be used for the solution, meaning the phosphate is stirred into a salt solution and is soluble—a property that phosphates or phosphate combinations known so far do not have.

Table 4: Synergistic effect of the mixture according to the invention on the solubility and stability in salt-containing aqueous solutions (brines).

EXAMPLE 1

Solubility in Salt-Containing Aqueous Solutions (Brines)

The amount of 5 g phosphate (phosphate mixture) is dissolved by stirring it into 75 g water and the amount of 20 g cooking salt is then added. The brine is analyzed to determine whether it is stable over a longer period of time (16 h), meaning no precipitation (excess solute) occurs. Analysis of brine stability of different phosphates/phosphate mixtures in the system with 5% phosphate, 20% NaCl and 75% water phosphate mixture according to the + invention pentapotassiumtriphosphate (KTPP) +*) pentasodiumtriphosphate (NTPP) − tetrapotassiumdiphosphate (TKPP) − NTPP/TNPP - 90:10 blend − sodiumpolyphosphate + *)Following the preparation, a cloudy solution results with low precipitation (excess solute) after 16 hours. Evaluation: + = stable brine − = precipitations/excess solutes occur

EXAMPLE 2

Solubility in Salt-Containing Aqueous Solutions (Brines) in a Traditional Sequence

The amount of 8 g phosphate (phosphate mixture) is dissolved by stirring it into 68 g water. Subsequently, the amount of 24 g cooking salt is added and the brine is then analyzed over a longer period of time (16 h) to determine whether it is stable, meaning no precipitations (excess solutes) occur. Analysis of the brine stability of various phosphates/phosphate mixtures in the system containing 8% phosphate, 24% NaCl, 68% water phosphate mixture according to the + invention pentapotassiumtriphosphate (KTPP) − (no stable brine after 16 h) clear soluble KTPP − (no stable brine after 16 h) (NTPP) − (not soluble in brines) tetrapotassiumdiphosphate (TKPP) − (not soluble in brines) pentasodiumtriphosphate (NTPP) − (not soluble in brines) tetrasodiumdiphosphate (TNPP) 90:10 blend sodiumpolyphosphate − (no stable brine after 16 h) Analysis: + = stable brine − = precipitations/excess solutes occur

EXAMPLE 3

Solubility and Stability of Phosphates in Salt-Containing Aqueous Solutions (Brines) for Inverse Preparation of the Brine.

The amount of 22 g of cooking salt is dissolved by stirring it into 72.5 g water. Subsequently, the amount of 5.5 g phosphate (phosphate mixture) is stirred in. The brine is then analyzed over a longer period of time (16 h) to determine whether it is stable, meaning that no precipitations (excess solutes) occur. Analysis of brine stability of different phosphates/phosphate mixtures in the inverse system containing 22% NaCl, 72.5% water, 5.5% phosphate phosphate mixture according to the + invention pentapotassiumtriphosphate (KTPP) +*) clear soluble KTPP − pentasodiumtriphosphate (NTPP) − tetrapotassiumdiphosphate (TKPP) − NTPP/TNPP —90:10 blend − sodiumpolyphosphate (P₂O₅ = 60%) − sodiumpolyphosphate (P₂O₅ = 68%) + *)Following preparation, a cloudy solution is obtained and after 16 h precipitations (excess solutes) occur. Evaluation: + = stable brine − = precipitations/excess solutes occur 

1. The use of a phosphate mixture composed of: a.) 60 to 85 weight % of a clear soluble potassiumpolyphosphate with a P₂O₅ content of 46.0 weight % to 47.0 weight % and a K₂O/P₂O₅ mole ratio of 1.7 to 1.78, b.) 15 to 39 weight % sodiumpolyphosphate, c.) 1 to 5 weight % XH₂PO₄ and/or X₂H₄P₂O₇, with X═Na and/or K, wherein the mixture has a pH value of 8 to 10, preferably 8.5 to 9.5 and cloudiness in water and brines of <5 TE/F, for use in the production of phosphate-containing brines in the food industry.
 2. The method for producing phosphate-containing brines, composed of 60 to 85 weight % of a clear soluble potassiumpolyphosphate with a P₂O₅ content of 46.0 weight % to 47.0 weight %, preferably 46.4-46.8 weight %, in particular 46.4 weight % and a K₂O/P₂O₅ mole ratio of 1.74 to 1.78, preferably 1.73 to 1.75 and in particular 1.74, further composed of 15 to 39 weight % sodiumpolyphosphate and 1 to 5 weight % XH₂PO₄ and/or X₂H₄P₂O₇, with X═Na and/or K, characterized in that potassiumphosphate salts or potassiumoxide and P₂O₅ are mixed at the desired potassium:phosphorus ratio, that the mixture is heated to the melting temperature and is kept at this temperature until a balanced reaction forms, that the mixture is then drained, finely ground and mixed at the specified ratio with correspondingly ground powders of sodium polyphosphate, XH₂PO₄ and/or X₂H₄P₂O₇, with X═Na and/or K. 